Spicelib

A thin MCP server that wraps spicelib for circuit simulation. The heavy lifting, such as simulator invocation, .raw file parsing, and multi-simulator abstraction, is done by spicelib, which deserves most of the credit. This project is purely a transport layer that exposes spicelib's functionality as MCP tools for use with Claude Code (and other coding agents).

Primary use case: behavioral model fitting — run simulations, compare against real measurements, iterate on SPICE models.

Tools

• run_ac_analysis — AC frequency sweep, returns magnitude/phase data
• run_transient — transient simulation, returns time-domain waveforms
• run_dc_op — DC operating point analysis
• run_sweep — run multiple simulations in parallel, sweeping component values

Results are saved as .npz files alongside the netlist for further analysis and plotting.

Supported simulators

Simulator	SPICE_SIMULATOR value	Install
ngspice	ngspice (default)	sudo apt install ngspice
LTspice	ltspice	Download from Analog Devices
Qspice	qspice	Download from Qorvo

Set the SPICE_PATH environment variable to override the simulator binary location.

Setup

Copy .mcp.json.template to .mcp.json in your project directory and adjust SPICE_SIMULATOR if needed:

{
  "mcpServers": {
    "spicelib": {
      "type": "stdio",
      "command": "uvx",
      "args": ["spicelib-mcp"],
      "env": {
        "SPICE_SIMULATOR": "ngspice"
      }
    }
  }
}

Requirements

• Python 3.10+
• A supported simulator installed and on PATH

License

GPL-3.0-or-later